HPV and virus-free PL
From: new2aquaculture@yahoo.com
To: shrimp@yahoogroups.com
Sent: July 28, 2004
Question:
Is there an acceptable infection level for HPV that
still allows for
stocking? For example, some farms stock PL with 20 - 30 % MBV. Is
there a threshold?
If we say only 100 % virus free PL (except of course WSSV free), we
are not sure if any farms are able to stock PL. For years here in S. East
Asia nobody has checked for all viruses, only WSSV. Now with more
accessible PCR tools, more viruses are detected in PLs, which
previously was never a concern since it was never checked.
e-mail: new2aquaculture@yahoo.com
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Comments 1:
After ten years of experience worldwide comparing SPF
(virus-free) PL against others, it is clear to me that farmers should only
use virus-free shrimp. There is no minimum acceptable level of
virus.
If shrimp farmers only purchased virus-free PL, there would be enough
virus-free PL to supply the entire industry.
Jim Wyban PhD
High Health Aquaculture Inc.
ph/fax: 808.982.9163
e-mail: wyban@gte.net
www.hihealthshrimp.com
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Comments 2:
I totally agree with you regarding the importance of SPF status while stocking PL, but in many locations/seasons, especially in species like P. monodon this may become difficult due to dependence on wild brood stock which has very high incidence of virus in some seasons.
Anil Ghanekar
e-mail: anilghanekar@yahoo.com
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Comments 3:
Your comment just stresses higher what Mr. Wyban was
meaning.
The shrimp FARMING sector should support more of the HATCHERY investment and
development. As Mr. Wyban was implying, establishing a SPF program is a
heavy investment for a hatchery that will be done only if there is a buying
and discerning market for it....
Dependence on wild broodstock is not environmentally responsible and neither
sustainable. It is just a shortcut.
Breeding P. monodon broodstock is not impossible; maturation of monodon is
also well practiced.
It is up to the shrimp farmers to support establishments of SPF/R, breeding
selection and sustainable hatchery practices in their region by purchasing
such kind of larvae, even if they are more expensive.
Eric Pinon
e-mail: epinon@serviceaqua.com
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Comments 4:
I totally agree with you that in the future, SPF will
be the only way to
go. You are headed in the ONLY direction that will be the future of the
industry. But now, I don't see any SPF stocks that do well in Belize. But
keep up the good work. It will be here soon.
Hank Bauman
e-mail: Bauman.BAL@starband.net
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Comments 5:
You are bang on target.
Difficult but certainly not impossible.
Would require a huge effort in terms of time, technology development,
funding and co-operation.
e-mail: anilghanekar@yahoo.com
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Comments 6:
So what is it with Belize? Do we have a more rapidly
mutating strain of TSV here? I hear that the SIS is doing very well in
Asia also.
This past year at BAL we saw what I believe was a TSV
"hit" again.
Perhaps our SPR strains have about 60% totally resistant, 10% non resistant
and 25-30% that depend on good or bad conditions.
We had a cold winter. (23.8°C average from Dec-Mar
vs 26.2 for the same period the previous two years). Once the weather warmed
up we would see large amounts of feed consumed (up 500 lbs per acre per day)
followed by 1.3 gm weight gain, then 10,000 dead shrimp coming out of our
drains. We would see scarring in sampled shrimp also. Could it be that we
are losing resistance? Or, is there a new strain of TSV developing as we
speak?
I would think it's prudent to develop strains that work
against Belize
TSV simply because our strain is likely to spread throughout the region.
And, hope for a mild winter.
Hank Bauman
e-mail: Bauman.BAL@starband.net
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Comments 7:
Thank you for the various inputs about SPF/(R) etc.
There is still a
general reluctance to implement or accept PCR screening with cost
perception attached. Such irony, penny wise but pound foolish... many
farms want to save on screening cost but end up losing whole cycles
back to back. It is after being hit hard and suffering serious
losses, operators wake up to the fact that... PCR has become an
important part of disease and farm management.
Newer
e-mail: new2aquaculture@yahoo.com